A known sheet material gathering system is utilized to produce different magazines composed of different predetermined combinations of signatures for different groups of subscribers classified in accordance with predetermined criteria, such as age, income, occupation, geographic location, etc. This known gatherer system includes a plurality of hoppers or pockets which are located at feed stations and contain different signatures. A control apparatus provides for the feeding of signatures from at least some of the pockets onto a conveyer to make up magazines which are labeled with the name and address of the subscriber to which they are to be sent. The control apparatus effects operation of the various signature feed mechanisms to feed a combination of signatures which is appropriate for the subscriber who is to receive a magazine. One known system for producing different magazines in this manner is disclosed in U.S. Pat. application Ser. No. 141,331, filed May 7, 1971, by Donald C. Harder and Victoriano F. Rana and entitled "Method and Apparatus for Producing Magazines or the Like."
Since the different magazines have different signatures depending upon the subscriber to whom the magazine is to be sent, some of the signature feed mechanisms must be intermittently operated. Thus if magazines which are to be sent to subscribers in a northern geographic area have a special combination of signatures, certain feed mechanisms are operated to feed signatures for magazines which are to be sent to the northern subscribers. The sheet feed mechanisms which feed special signatures for magazines to be sent to northern subscribers are rendered ineffective when feeding signatures to form magazines which are to be sent to southern subscribers. Since the sheet feed mechanisms which form special combinations of signatures are operated intermittently, the probability of a malfunction is far greater than if the sheet feed mechanisms were operated continuously.
Assuming that there is a malfunction in the sheet feed mechanism so that a signature fails to feed or is incorrectly fed, a whole group of signatures must be discarded. Even if the controls for the gatherer are constructed so that the sheet feed mechanisms downstream from a malfunction are rendered ineffective to reduce scrap material, the total productivity of the gatherer is decreased since the imperfect group of signatures will pas through the machine and the downstream sheet feed mechanisms will be inactive.